JPH09102666A - Film formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a film such as conductive film on a thin ceramic board or on a baked film formed on a ceramic board, without generating cracks. SOLUTION: A ceramic board 40 or a baked film formed on the ceramic board 40 is coated with a filmy body 46, which is to be a metal film or a ceramic film, by baking. The filmy body 46 is trimmed by irrdiation with energy beams which decompose and remove the filmy body 46 without damaging the ceramic board 40 or the baked film to be unusable. Then, the filmy body 46 is baked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for forming a film on a ceramic substrate or a fired film formed on the ceramic substrate, and particularly to a method for trimming the film with an energy beam such as laser irradiation. Regarding

[0002]

2. Description of the Related Art Conventionally, in manufacturing a sensor, a resistor element or the like, a step of forming a film, particularly a conductive film, on a ceramic substrate has been used. These conductive films act as, for example, electrodes, resistors, leads, output terminals, etc. depending on the application. The film forming method includes print coating, blade coating, and spray coating. In a commonly used film forming method, a paste is printed on a ceramic substrate that has already been sintered to coat the film, the film is baked, and then the film is cut by laser trimming or the like. By coating by printing, even a film having a complicated pattern can be efficiently formed, and the thickness of the film can be adjusted by the viscosity of the paste. Then, the film width, resistance, etc. can be adjusted by the trimming process.

[0003]

With the recent miniaturization of sensors, resistor elements, etc., the ceramic substrate covered with a film tends to become thinner. However, as the ceramic substrate becomes thinner, cracks are more likely to occur in the ceramic substrate when the film covering the surface of the ceramic substrate is shaved. When cracks occur, the mechanical strength decreases and it becomes unusable for practical use. On the other hand, a method of improving the printing accuracy without removing the film has been tried. In this method, even if an attempt is made to adjust the line width only by printing, the edge of the line is bleeding, and thus there is a limit in adjusting the line width. Also, the material of the paste for printing is limited. Furthermore, the steps of cleaning, resist coating, etc. have become complicated.

[0004]

Therefore, an object of the present invention is to provide a method for forming a film on a thin ceramic substrate or a fired film formed on a ceramic substrate without causing cracks. . However, the present invention is not only applied to a thin ceramic substrate, but can be applied to general ceramic substrates. According to the present invention, there is provided a method for forming a film on a ceramics substrate or on a fired film formed on the ceramics substrate, comprising:
A material that becomes a metal film or a ceramics film by firing is coated as a film body, and the ceramics substrate or the fired film is not unusably damaged in the unfired state and Energy to decompose and remove the body
There is provided a method for forming a film, which comprises irradiating a beam to trim the film, and then firing the film.

In the above description, “without damaging the ceramic substrate or the fired film unusably” depends on the purpose and conditions of use of the ceramic substrate or the fired film. If required, even if the irradiated portion of the ceramic substrate has been altered by the energy beam to some extent, it still has the required insulation resistance and is not damaged. Further, when the ceramic substrate is used as a seal member in another example such as a pressure sensor, if the required sealing property is still provided even if the irradiated portion of the ceramic substrate is deteriorated to some extent by the energy beam, It is supposed to be undamaged.

In the present invention, the ceramic substrate or the fired film is not unusably damaged in the unfired state of the film body,
Further, there is a step of irradiating an energy beam for decomposing / removing the film-shaped body to trim the film-shaped body. Examples of such an energy beam include laser irradiation and electron beam, among which laser irradiation is preferable. Such an energy beam that "disintegrates and removes the film-like body without damaging the ceramic substrate or the fired film" is, for example, in the case of laser irradiation,
The intensity is 10 J / cm ² or less of fluence (laser energy density per shot), and the wavelength is 4
It is preferably not more than 00 nm. Since the output of laser irradiation is small, damage to the ceramic substrate or the fired film can be reduced. Moreover, since the wavelength of the laser irradiation is such that the organic binder contained in the paste is easily photochemically decomposed, the organic binder contained in the film is easily removed. Furthermore, in order to allow the film to be scraped with a limited laser output, it was decided to trim not the film after sintering but the film before sintering. The present invention is an IC
It is also effective for the problem of making the pattern density finer in the package alumina substrate. That is, I
Although it is necessary to miniaturize the wiring pattern as the pad for wire bonding with C is miniaturized, it can be applied to such an application. Therefore, the term "trimming" as used herein does not only mean that the predetermined shape already formed by another method is simply fine-tuned to a desired accuracy, and it is evenly formed on the ceramic substrate or the fired film. It also includes the positive meaning of arbitrarily removing the film-like body coated on the substrate to form a desired shape.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the surface of a ceramic substrate or a fired film is coated with a film. The film-like body becomes a metal film or a ceramic film after firing.
It functions as an electrode, a resistor, a lead, an output terminal, and the like. Therefore, it is clear that it is not necessary to cover the entire surface of the ceramic substrate or the fired film with the film-shaped body. Further, there is no limitation on the pattern, shape, etc. of the film-like body, and it is appropriately selected according to the application of the film.

In the step of coating the film-like body, a paste (including an organometallic compound such as gold resinate) is used for printing,
It can be formed by coating by a thick film forming method such as a dipping method or a transfer method, of which the printing method is particularly preferable, and the paste is more preferably dried after printing. In the latter case, the step of trimming the film-shaped body may be between the printing step and the drying step, or may be between the drying step and the baking step.

It is desirable that the paste contains at least one of a metal powder such as platinum, an organometallic compound, a cluster compound, and a ceramic powder as main components, an organic binder and an organic solvent. Paste is 1
Organic binder is 1 to 100% by weight of main component
20% by weight, preferably 2-15% by weight, more preferably 3-10% by weight, even more preferably 5-10% by weight
It is desired to contain. As an organic binder,
Synthetic resins are preferred. In particular, those having a carbon-oxygen bond are preferable because they are easily decomposed by laser irradiation. Specific examples of the organic binder include acrylic resins such as acrylic acid esters and methacrylic acid esters; cellulose resins such as acetyl cellulose and ethyl cellulose; butyral resins such as polyvinyl butyral (PVB); vinyl acetate resins; ethylene acetic acid. Vinyl copolymerization (EV
A) Resin etc. are mentioned.

As the organic solvent used for the paste, alcohols such as methanol, ethanol, isopropyl alcohol, butanol, octanol, and terpineol; ketones such as acetone and methyl ethyl ketone; ethers such as cellosolve and carbitol; methyl acetate Various organic compounds that are liquid at room temperature, such as ethyl acetate, esters such as cellosolve acetate and carbitol acetate; aromatic compounds such as xylene and toluene, can be used. When the trimming step is between the printing step and the drying step, the solvent used for the paste preferably has a boiling point of 80 ° C. or higher at 1 atm, and more preferably 100 ° C. or higher.

In the present invention, the film-shaped body is trimmed with an energy beam such as laser irradiation. FIG. 1 (a)
It is a front view of the film-shaped body before trimming. On the other hand, FIG.
(B) is a front view of the film-shaped body after trimming.
In FIG. 1A and FIG. 1B, the film-shaped body is coated on a ceramic substrate or a fired film (not shown). In FIG. 1A, the edges 12a, 12b, 12c of the film body 12 are shown.
Has wavy edges due to bleeding during printing. Therefore, it is difficult to sufficiently control the resistance value of the film and to narrow the film width b1. In FIG. 1B, the edges 12a and 12b of the film body 12 are trimmed by laser irradiation. The edges 14a and 14b of the film body 14 are substantially straight lines and are substantially parallel to each other. Also, the film body 1
The film width b2 of 4 is narrower than the film width b1 of the film body 12.

FIG. 2 is a side view for explaining the trimming process of the present invention. The surface 28 s of the ceramic substrate 28 is covered with the film body 20. The film body 20 includes particles 24 that form the film body and particles 26 of an organic binder and an organic solvent. The particles 24 are, for example, metal powder. Only some of these particles are shown in FIG. When the energy beam 22 such as a laser irradiates the film body 20, the particles 26 of the organic binder and the organic solvent are decomposed, sublimated, and boiled. Thereby, the particles 24 are repelled and the film body 20 is trimmed. Therefore, it suffices to irradiate with an energy beam that decomposes, sublimes, or boils the organic binder or the organic solvent and does not damage the ceramic substrate thereunder unusably. In general, the energy intensity A for decomposing / sublimating / boiling an organic binder or an organic solvent and the lower limit energy intensity B at which the ceramic substrate is damaged are far apart from each other, and the range of the energy beam intensity E is B. The wider the range of −A is, the less accuracy is required, and if E is set to a value in the vicinity of A, there is no possibility of damage to the ceramic substrate. Furthermore, it is preferable that the metal is not present as particles, but a film-like body is formed from an organometallic compound that is present in the molecule at the atomic level, because trimming can be performed with the lowest strength.

On the other hand, FIG. 3 is a side view for explaining a conventional trimming process. The conductive film 30 has already been sintered, and the conductive film 30 is composed of many crystal grains 34. The conductive film 30 is the surface 38 of the ceramic substrate 38.
s. When the laser 32 irradiates the conductive film 30, the crystal grains 34 are melted and scattered to trim the conductive film 30. Therefore, it is necessary to irradiate with an energy beam that completely melts and removes the crystal grains of the sintered conductive film and does not uselessly damage the underlying ceramic substrate. Generally, the energy intensity A for melting and completely removing the crystal grains of the conductive film and the lower limit energy intensity B at which the ceramic substrate is damaged are very close values, and the range of the energy beam intensity E that can be taken is B- The narrower the range of A is, the higher the accuracy is required, and industrially, if the control width of E is limited, the yield is reduced.

In the present invention, the strength is fluence of 10 J /
It is desirable to trim the film-like body by laser irradiation of cm ² or less. Since the output of laser irradiation is small,
It is possible to reduce damage given to the ceramic substrate or the fired film coated with the film body. The intensity of the laser irradiation is preferably 8 J / cm ² or less, more preferably 5 J / cm ² or less. The intensity of laser irradiation can be reduced as the wavelength of laser irradiation becomes shorter. More particularly, preferably 5 J / cm ² or less to the film using a paste containing metal particles, also with respect to the film using an organometallic compound is preferably 2J / cm ² or less.

In the present invention, the wavelength of laser irradiation is 40
It is desirable that the thickness be 0 nm or less. This wavelength facilitates the photochemical decomposition of the organic binder. Wavelength is 30
It is more preferably 0 nm or less. In the present invention,
The wavelength is preferably 180 nm or more, and 200 n
It is more preferably m or more. The drying temperature of the film body depends on the type of solvent used for the paste, but is generally 8
The temperature is set to about 0 ° C to 200 ° C. The firing temperature of the film body is appropriately selected depending on the type of metal or ceramics forming the film body. Further, as a laser type, an excimer laser or a type that extracts high-order harmonics of a YAG laser is preferably used, and a multiple reflection type excimer laser (eg, manufactured by Mitsubishi Electric Corporation; Mitsubishi Excimer Work System MEX 24-M) ) And an excimer laser stepper are preferable because they can trim a large area with high precision and high speed.

In the film forming method of the present invention, when the ceramic substrate is thin, for example, the thickness is 50 μm or less, and further 20
It can be preferably applied even in the case of μm or less. As the material of the ceramic substrate, partially stabilized zirconia is preferably used as shown below. The fired film formed on the ceramic substrate may be, for example, a film having a function such as a piezoelectric film (PZT film). This PZT film can be produced by forming it by a thick film forming method such as a printing method, a dipping method, or a transfer method, and baking it. P
The thickness of the ZT film is usually 50 μm or less, and can be suitably produced even if it is 25 μm or less.

Materials that can be used in the present invention will be described below. There is no particular limitation on the ceramics used for the ceramic substrate. Examples thereof include stabilized zirconium oxide, aluminum oxide, magnesium oxide, mullite, aluminum nitride, silicon nitride and glass. Stabilized zirconium oxide has high mechanical strength and high toughness even when the vibrating part is thin,
It is particularly preferable because it has low chemical reactivity with the conductive film.

Stabilized zirconium oxide includes stabilized zirconium oxide (stabilized zirconia) and partially stabilized zirconium oxide (partially stabilized zirconia). Stabilized zirconium oxide does not cause a phase transition because it has a crystal structure such as a cubic system or a tetragonal system. on the other hand,
Zirconium oxide undergoes a phase transition between a monoclinic system and a tetragonal system at around 1000 ° C., and cracks may occur during this phase transition. The stabilized zirconium oxide contains 1 to 30 mol% of a stabilizer such as calcium oxide, magnesium oxide, yttrium oxide, scandium oxide, ytterbium oxide, cerium oxide or a rare earth metal oxide. The stabilizer preferably contains yttrium oxide in order to increase the mechanical strength of the vibrating portion. At this time, yttrium oxide is preferably contained in an amount of 1.5 to 6 mol%, more preferably 2 to 4 mol%. Further, it may contain aluminum oxide in an amount of 0 to 2.5 wt%. Further, the main crystal phase may be a tetragonal crystal or a mixture of a tetragonal crystal and a cubic crystal. Further, the ceramic substrate is composed of a large number of crystal grains, but the average grain size of the crystal grains is
The thickness is preferably 0.05 to 4 μm, and 0.5 to 2.
More preferably, it is 5 μm.

The membrane preferably contains a metal that is solid at room temperature. For example, aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, rhodium, silver, tin, tantalum,
Examples thereof include tungsten, iridium, platinum, gold and lead. It goes without saying that these elements may be contained in any combination. Platinum group metals such as platinum, rhodium, and palladium, or alloys containing these platinum group metals and containing an alloy such as silver-platinum or platinum-palladium as a main component are preferably used.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples. However, the present invention is not limited by the following examples. (Embodiment 1) As shown in FIG. 4, a ceramic substrate 40 is formed on each of 50 samples, the surface of the ceramic substrate 40 is covered with a film 46, and the film 46 is formed by laser irradiation. The film 46 was trimmed, the film 46 was dried, and then the film 46 was sintered. Then, the film width of the film-shaped body was compared with that after coating the film-shaped body and before trimming and after trimming and before drying.

The partially stabilized zirconia was doctor blade molded to obtain a molded film. The partially stabilized zirconia contains 94 parts by weight of zirconia and 5 parts by weight of a stabilizer such as Y ₂ O ₃ . The thickness of the molded film was about 15 μm. The formed film is sintered to obtain the ceramic substrate 40.
I got

Next, a film-like body 46 having a thickness of about 10 μm was printed on the surface of the ceramic substrate 40 using a paste. To this paste, 5% by weight of ethyl cellulose was added as an organic binder to platinum powder having an average particle size of 0.8 μm. Furthermore, terpineol was added as an organic solvent. The film body 46 is a ceramic substrate 40.
Had a printing width b1.

Next, the edges on both sides of the film body 46 were trimmed in the longitudinal direction to reduce the film width from b1 to b2.
That is, the edge 47 of the film body 46 before trimming became the edge 48 by trimming. At this time, an yttrium aluminum garnet laser having a wavelength of 267 nm using high-order harmonics was used. The laser intensity was 6 J / cm ² fluence, the laser repetition frequency was 2 kHz, and the film was scraped at a speed of 5 mm / s in the longitudinal direction. The width (m of the film body 46 before and after trimming
The data for m) are summarized in Table 1.

[0024]

[Table 1]

By trimming, the standard deviation of the width of the film 46 was reduced from 8 μm to 3 μm.
This data shows that the width of the membrane 46 became more uniform, and waviness, bleeding, etc. at the edges of the membrane were removed. The ceramic substrate 40 and the film body 46 are heated at 120 ° C.
The film-like body 46 was dried while being held at. Then, the film body 4
6 at a temperature of 1300 ° C. under an air atmosphere to form a film 46.
Was sintered.

(Example 2) Using partially stabilized zirconia, a reverse roll coater was used to form a thin molding film 50 having a thickness of 20 μm as shown in FIG. 5, and a doctor blade was used to form a thick film having a thickness of 150 μm. The formed film 51 was formed. Further, a window portion 52 having a width of 500 μm and a length of 2000 μm was formed by punching on the thick molded film 51 having a thickness of 150 μm. Next, the thin-walled molding film 50 and the thick-walled molding film 51 are laminated and fired to be integrated, and the width is 400 μm.
A ceramic substrate 54 having a thin portion 53 of m and a length of 1600 μm was obtained.

Next, as shown in FIG. 6 (a), the strip-shaped patterns 55 and 56 having a width of about 140 μm and a width of about 240 μm are coated with the same paste containing platinum as in Example 1 on the thin portion 53 by printing. did. After drying, the film was trimmed with a multiple reflection type excimer laser to have a width of 100 μm and a width of 200 μm, respectively, to obtain a film-shaped body having band-shaped patterns 57 and 58 as shown in FIG. 6B. After that, the ceramic substrate 54 was heated in an electric furnace to burn the film body. As shown in FIG. 6C, a paste containing PZT, an organic binder, and an organic solvent is used for the strip-shaped patterns 57, 58 on the ceramic substrate 54 thus obtained, and the PZT film 59 is printed and baked. Was formed.

Next, as shown in FIG. 7A, PZ
On the T film 59 and the ceramic substrate 54, a film 60 made of gold resinate was applied by printing and dried. Then, the fluence is 0.5 to 1.5 J / cm ² by trimming using a multiple reflection type excimer laser.
Then, electrodes 61 and 62 having a predetermined pattern as shown in FIG. 7B were formed and fired to obtain a highly accurate piezoelectric pressure sensor having two types of sensitivity levels.

(Embodiment 3) FIGS. 8 to 9 are explanatory views showing still another embodiment of the present invention. As shown in FIGS. 8A and 8B, a ceramic substrate 72 made of partially stabilized zirconia having a thin portion 70 and a large number of fine holes 71 having a diameter of 60 μm arranged in the thin portion 70, As shown in FIGS. 9A, 9B and 9C, a gold resinate paste is applied by printing as a strip pattern 73, dried, and then trimmed by an excimer laser with a fluence of 0.1 to 0.3 J / cm ^2. The wiring pattern 74 was cut out. In addition, 75 shows a trimming line. Next, the ceramic substrate 7 having this wiring pattern 74
By firing No. 2, an ion flow control head substrate could be manufactured.

[0030]

According to the present invention, the ceramic substrate or the fired film is trimmed by an energy beam that does not damage the ceramic substrate or the fired film unusably and is decomposed and removed. A film can be formed on a ceramic substrate or a fired film with reduced damage.

[Brief description of the drawings]

FIG. 1 is a front explanatory view of a film. FIG. 1A is before trimming. On the other hand, FIG. 1B is after trimming.

FIG. 2 is a cross-sectional view for explaining the film forming method of the present invention.

FIG. 3 is a cross-sectional view for explaining a conventional film forming method.

FIG. 4 is an explanatory diagram showing an example of a film forming method of the present invention. FIG. 4A is a cross-sectional view taken along the line AA of FIG.
FIG. 4B is a front view.

FIG. 5 is an exploded perspective view showing an example of a procedure for manufacturing a ceramic substrate having a thin portion.

6A and 6B are explanatory views showing another example of the film forming method of the present invention. FIG. 6A is a state in which paste is printed and applied on the substrate, FIG. 6B is a state in which trimming and firing are performed, and FIG.
(C) shows the state where the PZT film is formed.

7 (a) and 7 (b) are explanatory views showing another example of the film forming method of the present invention. FIG. 7 (a) shows a state in which a film-like body is printed on a PZT film and a ceramic substrate, and FIG. 7 (b) shows trimming. The respective states of firing are shown.

FIG. 8 shows a ceramic substrate having a large number of fine holes arranged in a thin portion, and FIG. 8A is a plan view.
8B is a sectional view taken along line BB of FIG.

9A and 9B show an example in which paste is printed and applied on a ceramic substrate and then trimmed. FIG. 9A is a plan view and FIG. 9B is a cross-sectional view taken along line CC of FIG. 9A. 9 (c) is a sectional view taken along line CC of FIG. 9 (a) (after trimming).

[Explanation of symbols]

12 ... Membrane, 12a ... Edge, 12b ... Edge, 12c
... Edge, 14 ... Membrane, 14a ... Edge, 14b ...
Edge, b1 ... Film width before trimming, b2 ... Film width after trimming, 20 ... Membrane, 22 ... Laser irradiation, 2
4 ... Membrane constituent particles, 26 ... Organic binder and organic solvent particles, 28 ... Ceramic substrate, 28s ...
Surface, 30 ... Conductive film, 32 ... Laser irradiation, 34 ...
-Crystal grain, 38 ... Ceramics sintered body, 38s ... Surface, 40 ... Ceramics substrate, 46 ... Membrane, 47
... Edges before trimming, 48 ... Edges after trimming, 5
0 ... Thin molding film, 51 ... Thick molding film, 52 ... Window part, 53 ... Thin part, 54 ... Ceramic substrate, 5
5, 56 ... Strip pattern, 57, 58 ... Strip pattern, 59 ... PZT film, 60 ... Film body, 61, 62 ...
-Film after trimming, 70 ... Thin portion, 71 ... Fine holes, 72 ... Ceramics substrate, 73 ... Strip pattern, 74 ... Wiring pattern, 75 ... Trimming line .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H05K 3/08 H01L 41/22 Z (72) Inventor Nobuo Takahashi 2 Suda-cho, Mizuho-ku, Nagoya-shi, Aichi No. 56 Insulators of Nihon Insulator Co., Ltd.

Claims (8)

[Claims] 1. A method for forming a film on a ceramics substrate or on a fired film formed on the ceramics substrate, which comprises firing a metal film or a metal film by firing on the ceramics substrate or the fired film. Energy for covering a material to be a ceramic film as a film-like body, and disassembling and removing the film-like body without undesirably damaging the ceramic substrate or the fired film in the unfired state of the film-like body A method for forming a film, which comprises irradiating a beam to trim the film, and then firing the film. 2. The film forming method according to claim 1, wherein the energy beam is irradiated by an excimer laser. 3. The intensity of the excimer laser is a fluence of 10 J / cm ² or less.
The method for forming a film according to the above. 4. The film forming method according to claim 1, wherein a multiple reflection excimer laser is used for the irradiation of the energy beam. 5. The film forming method according to claim 1, wherein the ceramic substrate is made of partially stabilized zirconia having a thickness of 50 μm or less. 6. The film forming method according to claim 1, wherein the baked film is a piezoelectric semiconductor film having a thickness of 50 μm or less formed by a thick film forming method. 7. The film formation according to claim 1, wherein the film-like body is formed by applying a paste containing a metal powder, an organic binder and an organic solvent by a thick film forming method. Method. 8. The film forming method according to claim 1, wherein the film-shaped body is formed by applying an organometallic compound by a thick film forming method.